Power mower transmission control



VVAug. ll, 1942. `A. F. MoYER ETAL 2,292,580

PONER MowER TRANSMISSION CONTROL Filed oct. 14, 1938 2 sheets-sheet 1 ,4,1405 E MOYEE CARL /ZucfrE/voogF ATTaRlgsY-S Aug-.11,1942.- F.NMOYERETAL r 2,292,580 1 POWER MOWER TRANSMISSION CONTROL f Filed Oct. 14, 1938' Sheets-Sheet 2 lPatented Aug. 1.1, 1942 UNlTEDjSTTES PATENT; OFFI? rownnmowingiitllSIONCommJ Amos F.

Moyer and Carl Buckendorf, Minneapolis, Minn.,v assignors. to 'I'oro` Manufacturing Corporation 'of Minnesotm Minneapolis,

Minn.`,`1a corporation of Minnesota y Y Y Application October 14, 1938, Serial No. 234,982

' `(ci. 's6- 2.6) f

* The present invention relates to improved transmission mechanism for use in machines which are driven intermittently from a constantly rotating motor, such. as in powerlawnV mowing machines, lawn rollers, household machines such as washers, driers, floor Sanders and polishers, motor operated tools, and the like. The

invention is applicable specifically "to powerdriven` lawn mowers, and is hereinaftery described with reference to such machines although the invention is obviously not limited `to usein such a machine. Y f

In lawn'mowing machines of the type that are driven by la constantly rotatingrmotornitjis necessary to provide apower transmission between the motor and the mower-which may be connected so as to drive the cutting `reel and wheels of the mower and disc'onnected to permit the motor to idle ,without driving the'mowing machine. V'I'his function,` and fthe analogous function in the powerjtransmissionsof Vmany other machines to which the invention is applicable, has heretofore been accomplished by pro- Y viding a clutch at some point in the power trans- Y mission system, and while this mode of construction has been satisfactory the mechanism is somewhat Aexpensive to build. Likewise, various power transmissions have been made in which a belt has been made slack in order' to slip when.

power is tojbe'disengaged anq'made tight when power is 'to be transmitted. These tight-loose belt drives operate best with flat belts, although they have been employed in some instancesfwith 'Tight-loose V-belt drives have been. l

V-belts. only partially successful due tothe fact'that as previously constructed, V-belt'diives transmitted a small amount of power when in the loose j' condition. `As a fesult the tig'ht-looserbeltl principle has not been applicable Iwhere a complete absence of power transmission is Adesired when the belt is in the loose condition. 5 y c n e An object of this invention is to provide a simplifled and stationary means to control aV-belt so that it will be substantially concentric Vwith the drive pulley and free therefrom when made s1ack,soas tol permit free slippagewithout any appreciable tendency-to drive while slipping.

A further object of the invention'is to provide a tightening and loosening devicefor a beltrvcombined with a two-step change of speedv ratio as speed reduction, whereby Vthe driven shaft and the motor are both located on fixed centers, but

the intermediate shaft is on aniovablevcenterr that is operated for tightening and looseningwtheV belt that extends thereto from thek drive pulley.4 55

3 Claims. 2

,substantially at axed radius from thefdrivenr Vshaft and may be connected therewith by such Vmeans as a permanentlyV tightened belt? or. by

chain and sprockets, or bygear's. By virtue :of the ytriangular arrangement ofV centersv (which may approximate a right triangle) operationV of l the intermediate shaft along its'path of motion will directly tighten or loosen the' belt that drives it from the motor. .Y

VIt is accordingly an'object ofthe inventionrto provid'ea power transmissionin which the tendency toward Ypower transmission is reduced 4to an V unobjectionableminimum when the beltV is .in

the loose condition. It is afurther object to provide a power transmission mechanism, 'includingY a member for .positioning the belt substantially concentrieally and substantially out of contaetwith the. rotating drive.V pulley when in a .position ingwhich power is nottransmitted,

i It isa further object of the-invention toprovide a power transmission arrangement, includying ardrivev shaft, a driven shaft and: an idler shaft which is transversely movable, by which' movement'a belt may be .slackened or tightened to vary the power transmitted, and in `which mechanism, such movement'of the idler shaft does not appreciably vary.

the idler shaft and the driven shaft;

When the" power transmitting mechanism kof the present invention is used on lawn mowing machines and the like deviceswhich are` guided 40 by a handle or handles, itY is desirable to pro videa control member upon a handle of the machine within easy` reachof the operator. 'I'he handles of-su ch machines are pivoted on the machineLL for free movement within a. definite range and thepower transmissioncontrol must accommodatethis freedom' of movement,` while at the-same time maintaining a; requisite precision of movement in the controla.l Itis, therefore, ,anvobject-of the invention to proyide an operator control device as va part of the power transmis-A sion mechanism Vwhich ismounted upon a machineguide handleand freelyv movable therewith .andat the `same `time .capable of precise Vcontrol of the power transmitting mechanism;

he Vdistance -betweer It 'isa further object of the invention to pro;

Figure 3 is a partial sectional view ofthe transy mission mechanism and the mechanism control linkages taken on line 3-3 and showing the mechanism adjusted to the power transmitting position.v

Figure 4 is a similar sectional view of the transmission mechanism and the mechanism control linkages showing the transmission mechanism adjusted to the position in which power is not transmitted.

Figure 5 is a fragmentary elevational view of the'belt guide4 bracket of the transmission mech- The lawn mowing machine shown in Figure l comprises a mwingunit generally designated III, having a frame consisting of side plates I I 'and a motor bed plate I2 which may serve to position the side plates in definite spaced relation with respect to each other. Each of the side Vplates carries a stub axle I3 upon which the wheel I4 of the mower is journaled. In Figure 1 the wheel I4 which is nearestrthe observer, has been shown as removed from stub axle I8 so as to reveal the mechanism behind the wheel.

At the trailing edge I6 of the side plate there -is revolvably mounted a ground roller I1 which 4 0- gine generally designated 38 which is bolted t0 the motor bed plate I2 by means of bolts 89. Bed plate I2 is preferably slotted at 88a so as to permit a forward and backward movement of the motor to allow belt adjustment when necessary, as hereinafter explained. .The motor is provided with a V-type driving pulley 4|! which is a mounted upon the motor drive shaft 4I.

serves to support the back end ofthe mower and which has the .usual adjustment. The cutting reel ofthe mowing machine has not been illustrated but the outside path of movement of the blades is shown by dotted circle I6. The reel is carried upon through shaft 20 and is driven by a sprocket wheel 2|. The outer end of shaft 28 carries a pinion gear 22 which meshes with an internal gear which is formed in the wheel* I4. The pathv of the internal wheelgear is i1- lustrated in the drawing at 23.-

In the usual lawn mower constructions the `reel 1 shaft pinion is driven -from the wheel gears through a rachet mechanism which according to usual practice is formed within thepinion gear. In the present invention the rachet mechanism (not shown) is reversed so that the pinion 22 drives the wheel gear 23, thus to propel the machine.- f

A guiding handle generally designated 25 is provided for the mowing machine and consists oi' a shank 26 preferably of rectangular vcrosssection which at its upper end carries a cross bar 21. The lower end of shank 26 can'ies a biiurcated fork 28 which has a spread sufliciently wide so that each prong of the fork overlies one of the side plates II, the two prongs being pivoted to the side plates II at 29. Although pivoted at 28 the guide handle 25 is permitted only a limited movement with reference to the mowing machine frame. This is accomplished by means of a pair of supporting rods Sli-30 which are connected to the fork at points 3| and disposed at an ele-A vation above pivots 29. In Figure 1 the rod 30 To the rear of the engine there is provided power transmission control mechanism generally designated 48 which comprises a control base 44 which is fastened to the motor bed plate I2 by means of studs 45, and a rocking counter-shaft assembly 48. The forward part of control base 44 is provided with a pair of opstanding ears 48 which carry a pivot shaft 41, upon which the counter-shaft assembly 4l is mounted. The rockingv countershaft assembly comprises a pair. of spaced legs 58 which are connected together at their upper ends by a tubular section 5 I The lower ends of the legs 5I are pivoted upon shaftI 41 and the tubular section carries counter-shaft 49 in bearings 52 that may be effectively lubricated from the chamber of tubular section 5I.

The rear portion of control base 44 is provided'with an inclined journal vseat 55 which carries a triangulariyshapedy crank sector 56. The sector 56 -has'a pivot shaft` 51int`egrally formed upon it, which fits into the iournal of seat 55 and is retained by cotter pin 58. The tubular vportion 5I of the transmission' rocking frame assembly 48 is provided with a rearwardly extending ear 68 whichis pierced to receive one end of `a coupling bar 6I, theother end of which is connected to a hole in the sector 56. Coupling bar 6I 'is Qheld in assembled relation byAcotter pins 62-62.

The rocking frame 48 may be biased to the forward position by means of a spring 65 which is looped around the pivot shaft 41 and has one end" in contact with the surface of'control base 44 and the other end hooked around one leg 5l) of the 'frame 48. The spring istensioned so as to tend to` move the y frame 48 counterclockwise around shaft 41 as a pivot. .y 4 The shaft 49 is provided at one end with a V- belt pulley 16 and at the other end with a chain sprocket 1I. The V- belt pulley is of a diameter somewhat larger than the drive pulley 46 of the motor to which it is connected by means of a V-belt 12. The Sprocket '1I is connected to the Illiel shaft sprocket 2i by means of a drive chain 'I'he motor bed' plate is provided with a belt supporting member generally designated 15 which comprises a round rod of steel or other suitable materialwhich is fastened toV the motor bed .plate I2 by meansV of nuts 16. The belt'guide comprises a lower-.vertical portion 11 and two spaced horizontal portions 18 and 19. The horizontal portions are spaced apart by a distance Just Ysuillcient to clear the upper and'lower -por` tions ofA the belt 12, when the belt is in the tight, or powertransmitting condition. The purpose of this arrangement will be hereinafter described with reference to the operation of the device.

which) is nearest the observer, and the near por- 'I54 The guiding handle ofthe mowing machine is v Y 2,292,580 provided with a control actuating shaft 80 which is mounted beneath and longitudinallyof the guide handle 25. The upper portion of theshaft 80 is bent outwardly for a short Vdistance as at 8| in Figure 3,*and then again at right angles up- -wardly as at 82. The outer end of portion 82 of moving the knob 83 and portion 82 downwardly,

the crank arm 85 assumes the.v position shown in Figure 4. The crank arm 85 is connected tosec-v tor 56 by means of a rod 88 which. is preferably' providedwith a turnbuckle adjustment .member 89. The rod 88 is held in assembled position on crank arm 85 by meanso'f cotter pin V90 and isv held to sector 56 by means of cotter pin 9|L Figure 3 and Figure 1 of the drawings illus`' 1 trate the'transmission mechanism in the power transmitting condition, whereas Figures 2 and 4 show the arrangement in the position in which no power is transmitted. 4It will be noted vthat when the transmission andE controls. are in the power transmitting position that knob 83 and portion 82 of the control mechanism have beenr moved upwardly in the direction of arrow 92 of Figure 3 untilthe portion 82 of the control rod abuts against the left side of guide handle shaft 25. In this condition crank arm 85 is vdownwardly to the left and sector 56 is in position such that coupling bar 6| will have moved slightly beyond the dead center position represented by the center of pivot shaft 51. The tension upon the belt 12 tends to pull the shaft 49 and the rocking assembly 48 in a forward direction, but since coupling bar 6| is'slightly to the left of dead center, as explained above, the tension will be resisted and a slight torque produced in a clockwise direction upon sector 56, thus producing a tension upon rod 88 which holds the control mechanism in the 4operated direction represented by arrow 92.

It will be noted that as the operating handle 25 is raised to the dotted sented by the rectangle 95 and the dotted line vposition 96 of rod 88, that this will produce a -very slightcorresponding displacement of section 56 to the dotted line position 98; On account of the proximity of sector 56 and rod 6| to the dead center relation, this slight displacement is accompanied by substantially no movement of rocking frame 48, and the belt 12, and accordingly does not change its power transmitting characteristics. Hence theA raising or lowering of the guide handle 25 throughout the range dened by nuts 33 on rod 30, has no noticeable effect upon the transmission whenit is in the power transmitting position.

In a slightly modied form, this control mechanism may include a stop for sector 56 so that it. Will not attain position 98 upon vertical movement ofl handle 25. In this form of mechanism, the knob 83 is preferably so located with respect to the bearing center of shaft 8D and the angular position of arm 85 that it will be retained by gravity in position for transmission of power, for

example by bending portion 82 toward the right from the position shown in Figure 3.

When the operating knob 83 is rotated down- Wardly in the direction of arrow to the posiline position repre- Y Y tion shown in Figure 4 crank arm 85 draws rod 88 to the right vand accordingly moves'sector 56 to the positionshown. 'I'he rod 6| is! likewise Ymoved to itsnew position and shaft 48 rand'rock-` I ing frame assembly 48 are moved forward in an slackening of amount to produceV a ksubstantial the'belt 12. It will be noted that in this position also that lraising the operating handle from the full line position to the dotted line position, represented by the rectangle 95 pivots the rod 88 about its connection to the ibell crank .plate 56 and moves the Vbell crankl plate an amount so smallas not to be capablevozf 'representation in the` drawings. Hence, the vmovement up vand down of guide handle 25 produces no'change inV the existing slack condition of the powerftransl fmitting thebelt .12',

'I'he belt 12 is Vofendless variety,V -belt `of ,mold'ed rubber and cord construction and in its slack conditionftends to assume a `nearly circular coniguration. Hence, as the rocking yframe 45 and pulley 10 are-moved to thebelt slack- -ening position shownvirif'iligures 2 and 4 Vthe upper portion |02 of the belt 12 tendsto arch` slightly and the'mower portion |03 tends to curveV downwardly. This tendency is resistedby the portions 18 and 19 of the belt guide 15 since-18 contacts with the lower portion |03 of the belt and 19 contacts with the upperportion |02. .The belt is accordingly forced to maintain its elongated condition even the slackened, and as a nate a separate pin-such as result is -held away from substantiallyV all portions of the belt-contacting surface of pulley 40. Should there occur only a slight contact between the belt and pulley 40, the only effect will beto vdrawthe .belt forwardly in its contact with portion 19 until contact with the pulley is eliminated. By theY arrangement shown, the belt is held in a condition substantially out of contact with the V-pulley 40 so ,49 andthe interconnected reel shaft 20 are accordingly noty revolved.

The position of the motor 38 is initially adjusted upon motor bed plate I2 by sliding it' to an appropriate position iny slots 39a, the bolts 39 then being drawn down tight. Adjustment vpin 41, which is located in accordance with lthe principles involved in this invention. By locating pin 41 on the line between the respective centers of shafts 48 and 20, the slight necessary movement of yshaft 49 may take place without effecting the engagement of chain 13 on sprockets 1| and 2|. pin 41 should occur when belt 12 is' tight, and the respective parts are in'l power-transmitting position. Obviously, when applying this invention, be feasible to extend the arms of'rocking frame 48 so as to elimi- 41, and cause frame 48 to pivot about the center of driven shaft 20.

When the power transmission control is in the Y the belt 12 is drawn power-transmitting position into contact with pulley interconnected reel shaft '40 and shaft 49 and 20 of the mower are (not shown) between pinion 22 of the reel shaft of .the wheels is arranged so that power will be that there is no appre-Y V ciable tendency to transmit power and pulley j 10, shaft .'Preferably, exact alignment of it would in many instances, Y

and internal gear 23 transmitted from the pinion 22 to the reel shaft 23. Wheels I4 are likewise driven as the cutting backward and forward while the cutting reel is revolving.

It is obvious that various modifications may be made in the apparatus shown without departing from the spirit of the invention shown and herein claimed as follows.

We claimz. Y

1. A power transmission control mechanism for a power transmission having a drive pulley, means mounting said pulleyfor rotation about an established axis, a driven pulley, a belt mounted on said pulleys, means for mounting vsaid driven pulley, for shiftable movement away from the drive pulley to tighten said belt and toward said pulley to loosen said belt, stationary means adjacent said drive pulley to support the belt Asubstantially out of contact with the drive pulley when the shiftable means is moved toward said drive pulley to loosen the belt, comprising means for moving said shiftable means including a crank plate, a mounting pivot for said crank plate, a link connected to said crank plate and .connected to said shiftable means, and means for rotating said crank plate to a position in which .the crank plate pivot is between the point of connection of said link and plate and the shiftable means and the link is substantially in line with said pivot.

2.,In a power driven operator controlled mal.chine of the walking type, having a machine frame, a motor thereon with a belt-type power transmission, including a shiftable frame carrying a belt pulley, and'an operator handle for controlling the' machine; an improved power transmission control for accurately tightening and loosening the belt from the operator handle position comprising, a shaft longitudinally of the handle havingan operator grip thereon for rotating the shaft, a first crank on the shaft adjacent the machine, a second crank pivotally mounted on the machine at a position alongside said handle, a rst link connecting said cranks whereby rotation of shaft by the operator rocks thesecond crank, and a second link connected at one end to the second crank and at its other end to said shiftable frame whereby movement of the second crank moves said shiftable frame. '3. The combination set forth in claim 2 wherein the pivot of the second crank is at a position intermediate the ends of the second link.

AMOS F. MOYER.

CARL H. BUCKENDORF. 

